The invention relates to a method of controlling quality in the production of ready-to-pour shells or core assemblies wherein a molding material is forced by means of a shooting device into an openable tool and solidified therein to form a component of a mold--core or shell--and wherein the mold component is removed when the tool is open, and thereafter handled in any desired order, transported, if need be, processed, and, if need be, completed to a mold assembly.
Basically the present invention relates to the field of foundry practice. To produce castings, foundry cores or foundry molds are generally made as separate parts, combined, and joined together to form a casting mold or core assembly. Thereafter, these core assemblies are filled with molten metal for producing, for example, a metallic workpiece. In mass production the core assemblies that are to be filled with molten metal pass one after the other through the production line.
In this connection, it is quite especially important that the workpieces cast in the core assemblies require an extremely long cooling phase, which will often last over several hours. Only after this cooling phase, is it possible to inspect the cast workpiece or product. Consequently, it is possible to find only several hours after casting and, thus, likewise several hours after the core shooting, whether or not the part cast in the core assembly is entirely free of defects.
In the event that a defective core is used, it will be possible to detect a reject resulting therefrom during the casting only hours after the production of the core. Should in this instance the defect on the core again be a systematic defect that recurs, for example, because of a defect on the tool, rejects will be produced for hours before the defect is found on the cast product. The defective cores that are accountable for these rejects may originate, as previously described, not only from defects in the tool of the core shooting machine, but also from direct damage to the cores during their handling, transportation, or assembly. In any event, it is not justifiable to be able to detect defects and, thus, rejects, only after completion of the casting operation, or during an inspection of the already cooled castings.
Moreover, damage to the mold components and/or tools may occur not only in the immediate vicinity of the shooting device, but also during any handling of the mold component and/or tool, during transportation, during a processing of the mold components, during cleaning of the tools, and in particular also during completion of the mold components to a mold assembly of any configuration.
Core and shell shooting machines of the above-described kind have been known from practice for decades. Only by way of example, reference may be made to DE 31 48 461 C1, which discloses a core and shell shooting machine.
DE 44 34 798 A1 discloses likewise a core and shell shooting machine, in which at least one visual inspection of the tool is provided. In the long run, the visual inspection disclosed in DE 44 34 798 A1 is impractical, inasmuch as the tool cannot be constantly observed, in particular within the scope of a fully automatic production. For a visual inspection, a skilled operator would have to observe the tool constantly, i.e. after each shooting operation. Even if such a visual observation or inspection were to go forward, the destiny of a core that is ejected and intended for further transportation, processing, or completing to an assembly would be left entirely open, since defects or damage may occur likewise during a manipulation or processing of the cores, during a transfer of the cores, or even during an assembly of the cores.
The same applies to the handling of the tools, in particular during a tool change, during cleaning, during transportation of the tools to a storage or during the removal of the tool from the storage or a magazine.
It is therefore the object of the present invention to provide a method of controlling the quality of ready-to-pour shells or core assemblies, which permits detection with a high probability of defects on the tool and, thus, of rejects, and which allows to prevent--systematically--repeating rejects.